Internal combustion engine, more particularly for motor vehicles, and means for limiting the emission of unburned gases

ABSTRACT

A system for diminishing atmospherical pollution due to the discharge of unburned gases and volatile fuels from motor cars in which an internal combustion engine already equipped with ducts connecting the base chamber of the engine with the intake manifold and the fuel tank has the end portion of the duct which connects the fuel tank to the inside chamber of the engine base is joined to the end portion of the duct connecting the intake manifold with the chamber. Hence, when the engine is not running, all the gases and vapors are stored in the interior chamber of the engine base, whereas, as soon as the engine runs, all gases and vapors are sucked by the engine cylinders to be burned therein.

[ 1 May 8,1973

United States Patent 1 Garcea e n 2. mm a r. d m o n 0 G a M t e e m m em r. re 3 Ht 8 as & m a 9 ea 1 .nm II 6 m0 u. 4 E 6 W n 7 r 1 .mo NH 3 PA [57] ABSTRACT A system for diminishing atmospherical pollution due to the discharge of unburned gases and volatile fuels [75] Inventor: Giampaolo Garcea, 18 Milan, Italy [73] Alfa Rome. S.P.A., Milan, Italy Nov. 23, 1970 Assignee:

[22] Filed: from motor cars in which an internal combustion engine already equipped with ducts connecting the base [2]] App]. No.: 92,084

chamber of the engine with the intake manifold and the fuel tank has the end portion of the duct which connects the fuel tank to the inside chamber of the en- [30] Foreign Application Priority Data Jan, 24, 1970 Italy................................19766 A/70 gine base is joined to the end Portion of the duct necting the intake manifold with the chamber. Hence,

[52] U.S.Cl....................................123/136,123/121 e the engine is not running, all the gases and .F02m 25/08 vapors are stored in the interior chamber of the engine 123/119, 119 B, 120, base, whereas, as soon as the engine runs, all gases and vapors are sucked by the engine cylinders to be burned therein.

[51] Int.

[58] Field of Search [56] References Cited 1 Claim, 3 Drawing Figures UNITED STATES PATENTS 3,513,818 5/1970 Wallin, Jr. ........................123/121 X INTERNAL COMBUSTION ENGINE, MORE PARTICULARLY FOR MOTOR VEHICLES, AND MEANS FOR LIMITING THE EMISSION OF UNBURNED GASES BACKGROUND OF THE INVENTION This invention relates to means for limiting pollution of the atmosphere by internal combustion engines. It is known that atmospherical pollution caused by motor vehicles driven by internal combustion engines is caused, or may be mainly caused, by the following reasons:

due to gases which have not been perfectly burned and are discharged in the atmosphere through the mufflers;

due to gases and fuel vapors which are formed in the base of the motor and are discharged into the atmosphere through the venting pipe of the motor base;

due to fuel vapors which are set free in the fuel tank or in the carburetor float chamber and are emitted into the atmosphere through the tank overflow pipe and the engine air intake, respectively.

In recent years, measures have been taken, or are about to be taken, to minimize not only the contents of components which have not been perfectly burned in the exhaust gases, but also the quantity of fuel vapors which, after having been evolved in the tank, the float chamber of the carburetor and the engine base, are emitted into the atmosphere.

As regards the problem of the fuel vapors which are evolved in the fuel tank, it is known that they can be evolved both when the car and the engine are at stand still, and when they are both moving. When the engine is stationary, obviously, the vapors cannot be drawn by the engine: these vapors, however, can be temporarily retained (so as not to flow outside, or to flow only to a minimum amount) by an activated charcoal filter or a chamber of appropriate capacity. The filter (or the chamber) not only is in communication with the tank, but also with the atmosphere and the engine air intake. Thus, after a stop, the engine, by drawing the atmospherical air through the filter (or the chamber) regenerates the filter (or scavenges the chamber by expelling the vapors). When the engine is running, and obviously through the devices enumerated above, the engine gradually draws the vapors which are further evolved in the tank: the vapors are thus burned in the engine and do not reach the atmosphere in their original condition.

Devices of this kind are known, the use of the engine base as a chamber inserted between the tank overflow pipe and the engine air intake is likewise known, for the same purposes as indicated above.

A defect which is common to all of these approaches is that relative to the increase of the contents of unburned components in the engine exhaust gases, inasmuch as the mixture becomes enriched above the normal rate due to the fact that the vapors are drawn in by the engine. This fact is experienced, more than all, as the engine is started and during the initial running period of the engine after a stop. If the regeneration, or scavenging, of the filter, or the chamber, respectively, takes place very quickly and at a low engine power output, a considerable amount of vapors is admixed with a small amount of drawn in mixture, so that the latter becomes enriched. Thus, the increase of the emission of toxic components in the exhaust gases takes place just as the car travels at a low speed, that which occurs in the inhabited areas, i.e. when the increase of these emissions is most detrimental. Automatic throttling valves have been suggested in order to overcome said drawback.

The magnitude of this defect can also be reduced, in the case of the chamber, by increasing the volume thereof, so that, at the end of the stoppage period, it will not only contain gasoline vapors, but an extremely diluted mixture of air and vapors; by so doing the engine, by drawing in at the start such a diluted mixture, does not enrich the mixture too much.

The approach consisting in using as a chamber the interior capacity of the engine itself to this purpose, is already known, as aforesaid. This approach, obviously, is extremely cheap especially in the case in which no throttling valves as indicated above are necessary. However, during progress of experimental tests and after a few thousand miles of road journeys, an increase of emissions in the exhaust have been ascertained when the engine was operated as usual during town travels (e.g. by carrying out the tests of the emissions accord ing to the methods as prescribed by the U.S. law) and it has been ascertained, moreover, that the exhaust emissions reverted to the starting values when fresh oil had been substituted for the old one. It has been ascertained, then, that the fuel vapors introduced, when the engine was running, in the interior capacity of the engine were partly absorbed by the oil. Under the running conditions similar to the running in town (for example during the tests performed according to the U.S. law) the hydrocarbons which had been dissolved in the oil, were evolved again as vapors. It is deemed that the phenomenon took place mainly during the exhaust stage due to the polluted oil sticking to the cylinder wall and thus heated by the preceding combustion stage. It was also deemed, however, that the phenomenon could have taken place in the engine base too, due to the polluted oil held thereby, so that the vapors could have passed, through the sucking device for the gases in the engine base, into the cylinders, thus enriching the mixture. The vapors, then could have been also passed through the piston rings during the exhaust stroke into the cylinder, thus becoming admixed, without being burned, with the exhaust gases and being discharged into the atmosphere therewith.

SUMMARY OF THE INVENTION An object of the invention is to overcome the defects enumerated above, and, to this purpose, it has been envisaged to use the device (with which the engines are already equipped) for drawing in again into the cylinders the gases and vapors which are formed in the inner chamber of the engine base. Such an action, as is well known, is obtained inasmuch as, downstream of the air filter, the ducts which feed the cylinders are connected, by one or more small ducts (for example one upstream of the throttle and another downstream thereof), to the inner capacity of the engine, generally with the top portion of said capacity, such as the valve control area of the engine head, an area which is in communication with the inner capacity of the engine base (this is limited, at the bottom, by the oil sump tank). It has also been envisaged to connect the top portion of the fuel tank with the inner capacity of the engine by a small duct whose end portion is inserted into the end portion of the duct (having a larger diameter) which, as aforesaid, connects the cylinder-feeding ducts with the inner capacity of the engine. By so doing, the result is that only when the engine is stationary the fuel vapors coming from the tank may reach the inner capacity of the engine for being temporarily stored therein. During the engine operation, the mass of gases and vapors which is evolved in the engine base inner capacity and which (due to the suction impressed by the cylinders) emerge through the larger diameter connection tube, prevents the vapors coming from the tank through the tube having the lesser diameter, from entering said inner capacity. The latter vapors, then, are combined with the gases and vapors which are present in the engine base and are also directly drawn into the cylinders.

In order that the features of the subject invention may be better understood, a description will be given hereinafter with reference to the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatical view, partly in section, of an internal combustion engine having in-line cylinders, constructed according to the invention, and

FIGS. 2 and 3 are cross-sectional detail views which show, in dotted lines, the flow lines of the fuel vapors and, in solid lines, the flow of gases coming from the engine base.

DETAILED DESCRIPTION OF THE INVENTION In the drawings, the numeral 1 indicates air filter with a relevant intake manifold 2, a main choke tube 3 with a throttle 4, intake valve 5, combustion chamber 6 as formed in head 7, cylinder 8 and piston 9. On the cylinder head 7 a timing cover 10 is applied, whereas oil sump tank 1 l is applied under the cylinder 8.

The head 7 is connected to the intake manifold 2 through a duct 12 which is branched into two ducts l3 and 14, and these latter ducts open into the manifold 2 upstream and downstream of the throttle 4, respective ly.

The numeral 15 indicates a duct having one end connected to the top portion ofa fuel tank 16, whereas the opposite end opens into the interior of the duct 12 in correspondence with the connection area of the duct 12 with the head 7.

The detail of this union of duct 15 into duct 12 can be more clearly seen in FIGS. 2 and 3.

In FIG. 2, the rubber or plastics hose constituting the duct 15 is slipped over a small tube 17 which is soldered to the duct 12. In FIG. 2, again, the dotted line arrows show the path of the fuel vapors which reach the top portion of the inner cavity of the engine base under the conditions obtaining with a stationary engine. The vapors, then, due to their heavier specific gravity, are shifted towards the bottom portion of the inner cavity of the engine base where they are temporarily stored.

In FIG. 3, which depicts the situation obtaining with a running engine, the dotted line arrows still indicate the path of the fuel vapors issuing from e tube 17, whereas the solid line arrows show the pat of the gas and vapor flow which evolve in the interior of the inner cavity of the engine base. Due to the larger rate of flow of these latter gases and vapors as compared with that of the fuel vapors coming from the fuel tank, the latter are entrained by the former and thus cannot enter, during the running of the engine (and thus of the car), the inner cavity of the engine base and are, conversely, drawn in too by the engine cylinders.

What is claimed is:

l. The combination with an internal combustion engine particularly for motor vehicles provided with a head, a combustion chamber in the head, a cylinder associated with the combustion chamber, a piston movable in the cylinder, a crankcase, an intake manifold leading to the combustion chamber, an intake valve for the combustion chamber, intake valve control means in the head, a throttle in the intake manifold and a fuel tank, of means for limiting the emission of unburned gases and volatile fuels from the fuel tank, the emission limiting means including a first duct, means connecting the duct for communication with the interior of the head, said duct having first and second branches communicating with the intake manifold upstream and downstream of the throttle respectively, a second duct of less cross sectional area than the first duct, said second duct having opposite ends, one end of the second duct being in communication with a top portion of the fuel tank, and the other end of the second duct communicating with the interior of the first duct adjacent the means connecting the first duct to the head, so that with the engine stationary, the fuel vapors emanating from the fuel tank are temporarily stored in the crankcase together with the gases and vapors evolved therein while with the engine running the fuel vapors emanating from the fuel tank and the vapors and gases evolved in the crankcase are directly drawn in by the cylinder.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. Iii-7311665 Dated May 8,1973

Giampaolo Garcea Inventor(s) It is certified that error appears in the above-identified patent and that Said-Letters Patent are hereby corrected as shown .below:

[73] Assignee: Alfa' Romeo S. p. A. Milan, Italy Signed and sealed this 27th day of November 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEY'ER Attesting Officer Acting Commissioner of Patents FORM PC4050 uscoMM-Dc scans9 1* us, covammzm FRINTINGIOFFICE: gsgdp-ass-su 

1. The combination with an internal combustion engine particularly for motor vehicles provided with a head, a combustion chamber in the head, a cylinder associated with the combustion chamber, a piston movable in the cylinder, a crankcase, an intake manifold leading to the combustion chamber, an intake valve for the combustion chamber, intake valve control means in the head, a throttle in the intake manifold and a fuel tank, of means for limiting the emission of unburned gases and volatile fuels from the fuel tank, the emission limiting means including a first duct, means connecting the duct for communication with the interior of the head, said duct having first and second branches communicating with the intake manifold upstream and downstream of the throttle resPectively, a second duct of less cross sectional area than the first duct, said second duct having opposite ends, one end of the second duct being in communication with a top portion of the fuel tank, and the other end of the second duct communicating with the interior of the first duct adjacent the means connecting the first duct to the head, so that with the engine stationary, the fuel vapors emanating from the fuel tank are temporarily stored in the crankcase together with the gases and vapors evolved therein while with the engine running the fuel vapors emanating from the fuel tank and the vapors and gases evolved in the crankcase are directly drawn in by the cylinder. 